# 整数和字符串是不可变对象，意味着可以用来共享
a = 3
b = 3
c = a
print(a is b)
print(a is c)

s1 = 'python'
s2 = 'python'
print(s1 is s2)

# 列表是可变对象
list1 = [1, 2, 3]
list2 = [1, 2, 3]
print(list1 is list2)
print(list1 is not list2)
